Conventionally, foam electroplating is carried out in a vertical electroplating cell. Such a cell comprises an electroplating bath and a cathode contact roll positioned outside the electroplating bath. A vertical planar anode is immersed in the bath. A strip of foam having an electrically conductive surface is continuously introduced into the bath and guided so that it travels past the anode prior to reaching the cathode roll. This cathode roll provides a cathode contact, which means that the strip of foam then functions as a cathode. Hence, when the strip passes in front of the planar anode, metal is electroplated on the strip.
Although electroplating in vertical cells is widely used, this technique shows some weaknesses. Firstly, the speed of electroplating in vertical, planar cells is relatively slow. Secondly, due to the specific resistance of the foam, a large voltage drop exists between the cathode and the electroplating bath. This may cause heating of this part of the strip and hence its damaging. Besides, as the strip is guided by the cathode roll and other idle rolls or driving rolls, the strip somewhat oscillates in the bath, especially as it passes in front of the anode, thereby causing local variations in the metal plating weight.
Document U.S. Pat. No. 4,326,931 describes a process for continuous production of porous metal. A non-conductive porous tape is treated to render it electrically conductive. The electrically conductive tape is then passed through an electrolytic bath in contact with a rotating cathode drum immersed in the bath to electrodeposit a layer of metal on the surface of the tape. Electroplating of the tape is further completed in a plurality of electrolytic baths to electroplate the tape to a desired thickness. In another embodiment, the cathode is formed by an electrically conductive belt immersed in an electrolytic bath and fed by a suitable driving means at a constant speed on a route defined by a plurality of guide rolls. Electric current is supplied to the belt from a pair of feeding terminals to the conductive belt to apply a predetermined voltage between the belt and the anode.
Document JP 63 089697 A relates to a method for plating a tape-shaped foamed body. The tape-shaped foamed body is passed through a first electroplating cell with a first side in contact with a cathode roll to plate the opposite, second face—faced outward—with a metal by about half of a predetermined amount. In a second electroplating cell, the second side is faced inward and brought into contact with a cathode roll to plate the first side of the tape-shaped foamed body by the remaining half of metal.